High-voltage disconnecting switch

ABSTRACT

A high-voltage rotary switch having a stationary main contact, a rotary main contact and an auxiliary arcing contact in electrical parallel with the rotary main contact. The arcing contact is the final circuit breaking element and is surrounded when the circuit breaks and arcing occurs by an arc-extinguishing chamber formed by two interacting arcuate elements one of which is stationary and the other of which is carried on the rotary contact.

United States Patent Inventor Hermann Pesch Witten, Germany Appl. No. 865,732 Filed Oct. 13, 1969 Patented Dec. 7, 1971 I Assignee Wickmann-Werke Aktlengesellschalt Wltten-Annen, Germany Priority Oct. 23, 1968 Germany P 18 04 661.2

HIGH-VOLTAGE DISCONNECTING SWITCH 5 Claims, 5 Driving Flip.

US. Cl 200/146 R, ZOO/144, ZOO/149 Int. Cl H0lh 33/12 Field of Search 200/ l 46, I49, 149.1, 148

[56] References Cited UNITED STATES PATENTS 2,337,889 12/1943 Harlow et al. 200/149 A FOREIGN PATENTS 721,386; 6/1942 Germany 200/148 11 Primary Examiner-Robert S. Macon Attorney-Brown, Murray, Flick & Peckham ABSTRACT: A high-voltage rotary switch having a stationary main contact, a rotary main contact and an auxiliary arcing contact in electrical parallel with the rotary inain contact. The arcing contact is the final circuit breaking element and is surrounded when the circuit breaks and arcing occurs by an arcextinguishing chamber formed by two interacting arcuate elements one of which is stationary and the other of which is carried on the rotary contact.

PATENTED DEC 7 l9?! SHEET 1 BF 2 INVENTORv HERMAN P656 Attorneys PATENTEDUEB Han 3.626.126

SHEET 2 BF 2 I N V E N TO R HERMAN PESCH Ar fornay:

1 HIGH-VOLTAGE DISCONNECTING SWITCH BACKGROUND OF THE INVENTION is ordinarily designed such that it can be rotated back and forth between a circuit-closing position and a circuit-opening position. In addition to the main contacts of the rotary switch, it is provided with an auxiliary arc-extinguishing contact which is the final circuit-breaking element and is surrounded by an arc-extinguishing chamber. Upon switching on, the flow of current is always initiated at the main contacts; however, when the circuit is broken, the main contacts break first, without arcing, followed by interruption of the circuit by the auxiliary arcing contact in an arc-extinguishing chamber.

Since prior art high voltage rotary switches are normally reciprocal in operation, movement of the auxiliary contact in the arc-extinguishing chamber is also subject to a change in direction after each switching process since opening and closing movements are usually in opposite directions. As a result, auxiliary contact assemblies are usually complicated and are very expensive, especially when used with tube quenching chambers. That is, they require pivot bearings, rods, and springs. Furthermore, they necessitate constant maintenance, because reliable operation is produced only with the correct time sequence during the switching phases. Wear phenomena, such as a change in the sliding friction of the auxiliary switch member, burning, sticking springs or spring fractures usually lead to difficulties in maintaining continuous operation.

Another disadvantage of such prior art high voltage switches employing auxiliary quenching contacts is that the auxiliary contacts form a secondary current path which is connected in parallel to the main contacts during most of the period of the on position of the switch. If, when the switch is closed, a short circuit condition occurs, there is the danger of welding of the auxiliary contacts which are of a much lighter design than the main contacts.

SUMMARY OF THE INVFNT ION As an overall object, the present invention seeks to provide a new and improved high voltage rotary switch which is much simpler in construction than prior art switches of this type.

Another object of the invention, is to provide a high voltage rotary switch which minimizes the danger of damage to an auxiliary arc-extinguishing contact under short circuit conditions.

Still another object of the invention is to provide a high voltage rotary switch of simple design incorporating means for insuring rapid extinguishing of arcs when the auxiliary contact breaks with a main contact.

In accordance with the invention, a high voltage rotary switch is provided comprising at least one stationary main contact energizable by the outer radial end of a rotary switch member rotatable in one direction only. An auxiliary switch contact is carried on the rotary switch member to make electrical contact with the stationary contact after the rotary member is disengaged from the main stationary contact. The invention includes a novel arc-extinguishing chamber which surrounds the auxiliary contact and the stationary main contact as the former disengages from the latter. This arc-extinguishing chamber is formed by a stationary arcuate member and a rotatable arcuate member carried on the rotary switch member and rotatable therewith. With this arrangement, the movable arcuate member slides past the fixed arcuate member during disengagement of the auxiliary contact while the two arcuate members, form an airgap therebetween which receives the arc.

In a preferred embodiment of the invention, the auxiliary arcing contact is carried in the movable arcuate member within a recess in such a way that it does not contact the main stationary contact until just before disengagement of the rotary switch member from the main stationary contact. In this manner, there is no current flow through the auxiliary arcing contact during the switching-on period but only during switching-off, thereby ensuring against welding of the auxiliary arcing contact under short-circuit conditions.

The above and other objects and features of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings which form a part of this specification, and in which:

FIG. 1 is a partially broken-away elevational view of the rotary switch of the invention;

FIG. 2 is a cross-sectional view taken substantially along line II-II of FIG. 1;

FIG. 3 is a cross-sectional view taken along line III-III of FIG. 1;

FIG. 4 is a cross-sectional view similar to that of FIG. 3 but with a somewhat different profile formation for the two parts of the extinguishing chamber; and

FIG. 5 illustrates the parts represented in FIG. I on a smaller scale, and specifically in the switched-off position.

With reference now to the drawings, and particularly to FIG. 1, a rotary switch member 2 is carried on a shaft 1 that includes knifelike movable contacts at both ends. Of the two movable contacts, only the lower one is visible in FIG. 1. Each end of the rotary switch member 2 is engageable with fixed main contacts 3 best shown in FIG. 2. It will be noted that there are two stationary contacts 3 between which the movable member 2 passes. The rotary member 2 rotates in one direction only as indicated by the arrow in FIG. 1.

The arc-extinguishing chamber for the switch assembly of the invention comprises two arcuate elements 4 and 5. Element 4, formed from insulating plastic material, is carried on the stationary contact 3 as shown. The arcuate element 5, also formed from insulating plastic material, is carried on the rotary member 2. Also carried on the rotary member 2, at the ends thereof, are auxiliary arcing contacts 6, only one of said contacts being shown in FIG. 1. The auxiliary arcing contact 6 is carried within a recess 10 in the arcuate element 5 and is provided at its radial outer end with a sliding surface 9 which engages a stationary auxiliary arcing contact 7 electrically connected to the main stationary contacts 3.

The two arcuate elements 4 and 5 formed from insulating material have cross sections such that they slide together in a tongue-and-groove configuration as shown in FIGS. 3 and 4.

Moreover, when the movable arcuate element 5 slides into the stationary arcuate element 4, an airgap 8 is formed between the two. The airgap can have either a U-shaped or a dovetailed cross section as shown in FIGS. 3 and 4, respectively, depending upon requirements. Furthermore, the cross section of the two arcuate elements 4 and 5 can have, if desired, a cross section which produces an airgap having steplike bends.

In the operation of the device, the main rotary switch member 2 passes between the stationary contacts 3, which are preferably spring-loaded, before the sliding surface 9 of the auxiliary contact 6 engages the stationary auxiliary contact 7. Hence, during the switching-on action, the auxiliary arcing contacts are not in engagement. However, before the main rotary contact 2 leaves the stationary contacts 3, the sliding surface 9 engages the stationary auxiliary contact 7. This ensures that if a high current surge is flowing between the contacts 3 as under a short circuit condition, the auxiliary contacts will not be in engagement long enough to cause welding of the tube because of their lighter construction.

Since the sliding surface on auxiliary contact 6 engages the stationary contact 7 before contacts 3 break, there is noarcing at the main contacts. However, by the time the sliding surface 9 of contact 6 breaks with the stationary contact 7, the downwardly depending projection on the arcuate element 5 has entered the groove within stationary arcuate element 4 to form the airgap 8 therebetween. When the contact 6 leaves the stationary contact 7, therefore, the two are enclosed within the airgap 8. The insulating materials from which the arcuate elements 4 and 5 are formed have the property that they fonn active gases under the action of the generation of heat which accompanies the arc. These gases assist in extinguishing the are. To ensure extinguishment of the arc with even greater certainty, the rotary part 2 describes a larger arc during switching-off than during switching-on, as can be seen from FIG. 5. That is, if the switching on process is thought to begin at the horizontal position of member 2 and end at the opposite horizontal position, switching-on occurs through an arc of about 100 and switching-off occurs through an arc of 80, i.e. the arc traversed by member 2 after contact 6 engages contact 7 and until member 2 again reaches a horizontal position.

Although the invention has been shown in connection with a certain specific embodiment, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention.

I claim as my invention:

1. In a high voltage rotary switch, the combination of at least one stationary main contact engageable by the outer radial end of a rotary switch member rotatable about in one direction only, an auxiliary switch contact carried on said rotary switch member to make electrical contact with said stationary contact after said rotary switch member is disengaged from said main stationary contact, and an arc-extinguishing chamber surrounding said auxiliary contact and said stationary main contact as the former disengages from the latter, said arc-extinguishing chamber being formed by a stationary arcuate member and a rotatable arcuate member carried on said rotary switch member and rotatable therewith.

2. The high voltage rotary switch of claim 1 wherein said stationary arcuate member and said rotatable arcuate member define, in cross section, a tongue-and-groove configuration wherein the tongue is separated from the groove by an arcextinguishing chamber.

3. The high voltage rotary switch of claim 1 wherein said auxiliary switch contact is carried within a recess in said rotatable arcuate member.

4. The high voltage rotary switch of claim 1 wherein said main stationary contact engages said rotary switch member before said auxiliary contact engages said stationary contact and said auxiliary contact disengages from said main stationary contact after said main contact have disengaged from said rotary switch member.

5. The high voltage rotary switch of claim 1 wherein there are two opposed main stationary contacts through which said rotary switch member passes. 

1. In a high voltage rotary switch, the combination of at least one stationary main contact engageable by the outer radial end of a rotary switch member rotatable about in one direction only, an auxiliary switch contact carried on said rotary switch member to make electrical contact with said stationary contact after said rotary switch member is disengaged from said main stationary contact, and an arc-extinguishing chamber surrounding said auxiliary contact and said stationary main contact as the former disengages from the latter, said arc-extinguishing chamber being formed by a stationary arcuate member and a rotatable arcuate member carried on said rotary switch member and rotatable therewith.
 2. The high voltage rotary switch of claim 1 wherein said stationary arcuate member and said rotatable arcuate member define, in cross section, a tongue-and-groove configuration wherein the tongue is separated from the groove by an arc-extinguishing chamber.
 3. The high voltage rotary switch of claim 1 wherein said auxiliary switch contact is carried within a recess in said rotatable arcuate member.
 4. The high voltage rotary switch of claim 1 wherein said main stationary contact engages said rotary switch member before said auxiliary contact engages said stationary contact and said auxiliary contact disengages from said main stationary contact after said main contact have disengaged from said rotary switch member.
 5. The high voltage rotary switch of claim 1 wherein there are two opposed main stationary contacts through which said rotary switch member passes. 